Geometric morphometric contribution to septal deviation analysis

Purpose The nasal septum presents inter-individual conformational variations. The objectives of this study were to establish a validated protocol for nasal septum analysis using geometric morphometrics (GM) to establish a classification of septal deviations (SD). Methods This was a retrospective study including two groups of patients: patients operated on by septoplasty (SD group) and patients without nasal obstruction (control group). The 3D segmentation model was extracted from CT scans. Thirty landmarks were defined on the nasal septum and validated by MANOVA Procrustes. Using a clusterization process, the septum was classified to reflect its different conformations. Nasal resistances were compared between the two groups. Results Fifty scans of patients with SD were included. The percentage of variability due to measurement error was 7.9% across all landmarks. We identified two clusters for the SD group. Using GM, conformation of cluster 1 (S-shaped) and cluster 2 (C-shaped) was visualized and identified. There was a statistically significant difference regarding nasal resistance between each cluster in the SD group compared with the control group ( p < 0.05). Conclusions This work is a first step in SD exploration, contributing to a clearer appreciation of the interactions between nasal conformation and function. An SD classification was devised based on a reliable and reproducible statistical analysis. Enhanced understanding of conformation/function interactions will improve the diagnosis and treatment of nasal obstruction.